• Basharat Ahmad Shah
• Abhishake Jain
• Dawood Masood

ABSTRACT Power quality is one of major concerns in the present era. It has become important, especially, with the introduction of sophisticated devices, whose performance is very sensitive to the quality of power supply. Power quality problem is an occurrence manifested as a nonstandard voltage, current or frequency that results in a failure of end user equipments. One of the major problems deal at here is the voltage sag/swell. A voltage sag or voltage dip is a short duration reduction in r.m.s. voltage which can be caused by a short circuit, overload or starting of electric motors. Voltage sag happens when the r.m.s. voltage decreases between 10 and 90 percent of nominal voltage for one-half cycle to one minute. The performance of a DSTATCOM in mitigating voltage sag/ swell is demonstrated with the help of MATLAB. The modeling and simulation results of a DSTATCOM are presented. D-STATCOM is promising device which is used for voltage sag, swell mitigation at distribution side. FACTS devices play an important role in improving the power quality problems, improving transmission capacity. To solve this problem, custom power devices are used. This Dissertation illustrates modeling and simulation of Flexible AC Transmission System devices in distribution network is presented so as to mitigate the voltage sag at the network buses. One of those devices is the D-STATCOM which is the most efficient and effective modern custom power device used in power distribution networks. DSTATCOM compensator is a flexible device which can operate in current control mode for compensating voltage variation, unbalance and reactive power and in voltage control mode as a voltage stabilizer. The latter feature enables its application for compensation of dips coming from the supplying network. In addition, the regulated VRMS voltage showed a reasonably smooth profile. This thesis explained the two level VSC based D-STATCOM and can be extended to multilevel inverter based D-STATCOM to reduce the harmonic content in current. The D-STATCOM can be designed using a current source inverter. An integrated D-STATCOM controller can be design for voltage regulation, reactive power compensation, This paper presents development, simulation and analysis of a D-STATCOM using MATLAB/ SIMULINK .To enhance the voltage sag restoration capability of the D-STATCOM. Accordingly, simulations are first carried out to illustrate the use of D-STATCOM in mitigating voltage sag in a system. Simulation results prove that the facts devices are capable of mitigating voltage sag as well as improving power quality of a system. The PQ disturbances of voltage magnitude variation such as sag, swell and interruption are created by applying different types of faults and heavy load in the power distribution model. The frequency variation types of PQ disturbances like harmonics are generated by applying power electronic converter. The non-stationary or transient PQ disturbances are produced by applying a capacitor switching bank in distribution model. The process has been done without connecting any FACTS device and then repeated once again by connecting D-STATCOM .The results obtained for the above cases have been compared to analyze the operation of D-STATCOM for improving the power quality disturbances. Results obtained shows that the developed D-STATCOM has good capability to starch the voltage level during voltage sag conditions.

Voltage sag, FACTS Devices, DVR, DSTATCOM, Reactive power compensation

"Improvement of voltage sag using FACTS device", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.7, Issue 6, page no.1619-1624, June 2020, Available :http://www.jetir.org/papers/JETIR2006567.pdf

"Improvement of voltage sag using FACTS device", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.7, Issue 6, page no. pp1619-1624, June 2020, Available at : http://www.jetir.org/papers/JETIR2006567.pdf